Modified Limb Lead (MLL) ECG recording systems are in use during exercise stress test and for enhancing the a trial ECG components (i.e.) P and Ta wave (atrial repolarization). Though the MLL system improves the amplitude and signal to noise ratio of a trial ECG components, information on the temporal aspects of these waves are scarce. Therefore, the aim of this study is to delineate the effects of a trial sinus rate in P wave and observable segment of the Ta wave in normal sinus rhythm (NSR) subjects efficiently. MLL ECGs were recorded from 50 NSR subjects (mean age 27 years, 20 women). The amplitude and duration of P wave and observable Ta wave were measured and analyzed. The P and Ta wave amplitudes correlated significantly (r = 0.28, p < 0.05) and the values of P and Ta wave durations did not correlate (r = -0.12, p > 0.05). Atrial sinus cycle length (PP interval) and heart rate variability (HRV) mainly affected the repolarization segment. © 2017 IEEE.